Repeat ablation with contact force sensing “does not necessarily guarantee a successful outcome” in persistent AF

Atul Verma

Preliminary results from the ABLATOR observational registry have shown similar success rates (around 58%) in first time ablation and repeat ablation for persistent atrial fibrillation (AF) ablation procedures with contact force sensing technology after one year of follow-up. A low risk of adverse events was also reported.

Presenting results from a subset of patients of ABLATOR at a Late-breaking trial session at EHRA-EUROPACE CARDIOSTIM (18‒21 June, Vienna, Austria), principal investigator Atul Verma (Southlake Regional Health Centre, Newmarket, Canada) highlighted the acute procedural success rate of 96.2% for first time ablation procedures and 93.6% for repeat ablation procedures. However, he also noted that freedom from AF, atrial flutter or atrial tachycardia greater than 30 seconds at one year after a single procedure was 58.3% for first time ablation procedures and 57.9% for repeat ablation procedures.

Verma told delegates: “The success rate is almost exactly the same at one year in both groups. If you take a patient for persistent AF ablation you may get six out of ten responding first time round and if you decide to take that patient back to the lab then you can expect a further six out of ten of those patients to have further success. So it is important to keep in mind that a repeat ablation does not necessarily guarantee a successful outcome.”

The ABLATOR ablation observational registry is a real-world study sponsored by Abbott where all patients indicated for an AF ablation had at least two Abbott devices in their procedures including: ablation catheter, steerable sheath, diagnostic catheter or mapping system.

Explaining the rationale of this registry, Verma said: “Contact force sensing catheters have become the gold standard technology for AF ablation when using radiofrequency energy; however, the data regarding outcomes of ablation for persistent AF using this technology are still limited as most of the trials have been designed for paroxysmal AF. Hence, we sought to prospectively determine the performance of a contact force catheter during ablation of persistent AF.”

In total, 2,035 patients were enrolled at 35 centres throughout Europe, Canada and Asia between 9 December 2014 and 7 June 2016. By the time of the presentation at EHRA the study was completing one year of follow-up.

The analysis presented at EHRA focused on a 346 patient subset treated with the TactiCath Quartz Contact Force Ablation Catheter (Abbott) for persistent AF for either their first (n=237, average age 62.4±9.9, 68.4% male) or repeat ablation (n=109, average age 63.6±7.8, 66.1% male).

After a 12-month follow-up, per standard of care according to the individual centre, 205 patients in the first time ablation cohort were included in the analysis and 100 patients in the repeat ablation cohort. Verma mentioned that all of the patient demographics were fairly typical of an AF population; however, he noted that in this registry the left atrial volume was studied to identify the true left atrial size (first time ablation cohort: 86.4±43.8ml; repeat ablation cohort: 86.2±41.9ml). He said: “Most of the clinical trials have shown the left atrial diameter and very few have described the left atrial volume, but I believe the latter is a better assessor of the true left atrial size.”

He also noted that most ablation procedures were carried out involving a pulmonary vein isolation strategy (96.6% in the first ablation cohort and 79.8% in the repeat ablation cohort).

Verma observed: “It is also interesting that in the era of contact force a very high percentage of operators have switched to point-by-point lesion only (50.2% in the first time ablation cohort, 54.1% in the repeat ablation cohort) rather than, for example, dragging lesion only (14.3% in the first time ablation cohort, 11.9% in the repeat ablation cohort).”

The total procedure time, radiofrequency time and fluoroscopy time for first time ablation group was 176.0±73.2, 39.3±25.3 and 18.4±11.7, respectively, and 174.6±83.7, 32.0±21.1 and 17.5±11.0 for the repeat ablation group.

“Safety is a very important concept and we know that early on with contact force catheter experience there were some potential concerns expressed,” noted Verma. However, in this registry, “overall there was a 2.3% (2.1% for first time ablation and 2.8% for repeat ablation) procedure and device related serious adverse event (excluding AF recurrence).” There were no deaths, strokes, oesophageal fistulae, myocardial infarctions or thromboembolisms reported.

In conclusion, Verma said, in a large, prospective registry ablation in persistent AF patients using the TactiCath Quartz Contact Force Ablation Catheter results in a 58.3% freedom from atrial arrhythmia with a very low risk of adverse events.

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